FIG 8.
Urea-dependent periplasmic pH restoration in acidic medium is lost in FlgS-deficient mutant. Cultures of H. pylori wild-type strain G27/PcagA-TorA-EGFP (A) and strain G27/ΔFlgS-PcagA-TorA-EGFP (B) were harvested and suspended in HP medium with 5 mM HOMOPIPES buffer (pH 5.0). At 60 s, 5 mM urea was added, and the fluorescence signal was converted to pH units, as described in Materials and Methods. For each strain, three independent cultures were tested. Error bars at 60, 70, and 240 s represent standard deviations of means (n = 3), and they are within the data point if not visible.